Generation of balanced pulse pairs based on a dual-chip coupling structure

Area of Science:

• Quantum Optics
• Integrated Photonics

Background:

• Asymmetric Mach-Zehnder interferometers (AMZIs) are crucial for quantum key distribution (QKD) systems.
• Current AMZI fabrication can be complex and prone to errors, impacting yield and cost.

Purpose of the Study:

• To propose and experimentally validate a novel dual-chip coupling structure for AMZIs.
• To enhance the manufacturing process, reduce fabrication errors, and lower costs for AMZI production.

Main Methods:

• Development of a silica-on-silicon planar lightwave circuit AMZI using a dual-chip design.
• Independent manufacturing of the variable optical splitter (VOS)-delay line (DL) part and the directional coupler (DC) part.
• Coupling of the independently fabricated chip components.

Main Results:

• Achieved balanced optical pulse pairs with a delay time of 402 ps under single-photon transmission.
• Measured an excess loss of 0.8 dB.
• Demonstrated reduced process difficulty and fabrication errors due to separate manufacturing.

Conclusions:

• The proposed dual-chip coupling structure offers a viable solution for mass production of AMZIs.
• This approach improves manufacturing yield and reduces overall production costs for QKD systems.